December Ground Motion Group Global Design Effort 1 LET Status report, December 06 Paul Lebrun Fermilab CD/AMR

December Ground Motion Group 2 Status, I Benchmark CHEF/Merlin, Misaligned and Steered Tesla design. –Tracking: Completed, results send to Jeff Smith, month(s) ago. Writing internal FNAL memo.. -DFS Steering: -Coding completed, analysis mostly done. -Documenting. DFS Steering Studies in CHEF On the above Linac, finishing up studies, documenting.

December Ground Motion Group 3 Benchmark, Fixed dipole setting Non trivial emit emittance growth! Ups and down because D taken out.. and coming back.. Agreement not perfect, sensitivity to small local difference in tracking.. Improves if Dispersion if corrected.

December Ground Motion Group 4 Status, I, II : DFS, in depth. DFS Steering Tricky if… Many variants of the basic DFS have been proposed, with not always good agreement between what works and does not work. A lot of dedicated software is needed, to duplicate these algorithms. Tedious to document ( rarely done!) Semi-Qualitative agreement between codes on the performance (Emittance vs S), substantial disagreement on what the “best” solution (dipole corrector settings) really is..

December Ground Motion Group 5 Benchmark, Fixed dipole setting Sorting this out took considerable amount of time…

December Ground Motion Group 6 Status, I, II : DFS, in depth. DFS Steering Tricky, one “root” cause Many perturbations of the orbit occurs with too few “knobs”, or dipole corrector. Cavity tilts: 24 of them per dipole correctors. Individual cavity tilts : ~200 micro-radiants Quadrupole displacements: ~ 350 microns At ~5 GeV, integrated kicks over 2 cryo-modules (24 cav.) delta y’ about the same size as the kick given by the quadrupole..

December Ground Motion Group 7 Kicks, Cavity vs Quadrupole. Plot has been produced, hopefully correctly. No time to included in this talk..

December Ground Motion Group 8 Accurate tracking through Cavities If cavity rotation matter, Shouldn’t be worried about tracking accuracy.. With rotated fields With realistic field map (kick depends on XY) A solution (Lynn Garren): G4 Runge Kutta integration G4/CHEF integration: allows to simulate halo, and interaction of halo with cavities…

December Ground Motion Group 9 Other Actuators In Bunch Compressor and early LINAC, exploring the possibility of tilting either cryo- modules or individual cavities. –Not Baseline ( = Not to be investigated. (?)) –Beam Based Alignments Algorithm for back- tilting do exist, just the right variant of DFS. –Coded in CHEF, running, need to document performance.

December Ground Motion Group 10 Dynamical DFS In CHEF, DFS was re-implemented keeping in mind the need to establish steering while the machine, burping, ( not belching?), creaking and moaning. –Iteration and convergence criteria. –Rudimentary controls ( beam permit dropping when x mm excursion at BPM Pause while we change DFS section. –Crude visualization, analysis code.. ATL Ground Motion integrated. Ready to Crank at bit more jobs.

December Ground Motion Group 11 ILC Main Linac Lattice. In CHEF, –Using corrected sBend/rBend code, got a matched bunch through the LINAC, with fraction of emittance growth. But the Dispersion at injection is close to 0. ? Am I really bending? Need checking. If checks, start DFS steering into it. –Few days of work to check if CHEF/DFS implementation good enough..

December Ground Motion Group 12 Plans, Short term Finishing documenting DFS steering, cavity tilt relevance. Prepare talk for Daresbury meeting. Keep running dynamical steering Dynamical Steering with ILC-ML Lattice, after tuning static tuning.